This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

Once forgotten and built over, this historic Black cemetery now houses a poignant memorial.

Once the largest trading firm of enslaved people in the U.S., this building is now a museum that preserves Alexandria's dark past.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

A blank headstone topped with a pile of pennies marks the final resting place of the infamous assassin.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

It's a pretty creepy lock-up.

A tribute to Ponce de Leon's supposed quest for eternal youth.

Two men built this castle on the Florida coast as an artistic “landscape sculpture.”

This unusually shaped fortress houses a blend of centuries-old frescoes and modern art.

A semi-abandoned village destroyed by U.S. bombings during World War II dominates the valley of Turano.

The scant remains of this flooded historic village can be explored in one of the most remote areas of the Great Smokies.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

An unusual resting place built into the hill with an amazing view of Lake Como.

The trials and tribulations of marking Poe's grave.

A model home in the Medical Examiner's Office in which grisly death scenes are staged to train forensic investigators.

Eighteen miniature death-scene dioramas.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

The highest waterfall between the Rockies and the Appalachian Mountains.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

The lasting remains of the region's once booming cement industry.

A unique sculpture designed to raise stroke awareness.

The last funhouse of its kind, where guests enter through the mouth of an 80-year-old blue whale.

A former Tibetan monk made a name for himself selling some of the best beef momos in New York.